CAT does coolant analysis, just like they do oil analysis. You can send them a sample from each engine and they can give you a report on all sorts of things. I think they often have multiple price points of testing, simple showing the chemical composition of the coolant and current level of protection (FP, BP, anti-corrosion, pH, conductivity). Next level analyzes contaminants and likely sources, e.g. corroded metals, scaling, etc.
If you send your oil to a CAT dealer for analysis -- you can likely send your coolant same place. I'd recommend giving them a call. If not, I'd call whoever you send your oil to. If you don't send oil out, or whever does your oil can't do coolant, I'd call the nearest CAT dealer or CAT-SOS-service provider.
Or, finding the nearest CAT dealer and calling them.